In the field of traditional print publishing, publishers of magazines and other periodicals typically sell advertising based on an estimated “total audience” reached by a particular publication. The estimated total audience differs from the number of copies printed or sold because each copy may be accessed by multiple people during its lifespan. Therefore, to calculate the total audience, print publishers have historically relied on surveys or panels to estimate the number of people reached by a single copy of the publication. The estimated number of readers per copy is then extrapolated to the total circulation. For example, if a particular issue sells 100,000 copies, and if reader surveys find that a single copy reaches 2.1 people on average, then the total audience may be estimated to be 210,000 individuals. However, because of flaws inherent to the survey-based methodology that is used to collect reader information, the current audience calculations may be flawed and inaccurate measures of the true audience reached by a publication.
Many publishers are now creating digital editions of their traditional print publications. The digital editions are distributed through digital channels and read on digital devices (e.g., tablet devices, personal computers, e-readers, mobile phones, laptop computers, etc.). To measure the circulation of these digital editions, a cookie or device identifier associated with each digital reader may be passed to an analytic system along with usage information when the digital readers access digital content. Other measures of circulation may be based on the number of digital periodical copies sold to readers. However, while these existing measures may be effective at determining the total number of copies that are distributed, the existing measures do not provide the total audience of a digital magazine. In particular, the existing measures do not account for the possibility of multiple people accessing the same digital content on the same device.
For example, a household of three people may have a single tablet device that is shared by all members of the household. Digital magazine purchases delivered to the tablet device may be accessed by all three people within the household. Although the audience for the digital magazine may include all three people who access the digital edition on the tablet device, the existing measures of circulation would attribute all usage on a single device to a single user. Therefore, the existing measures would incorrectly increment the “circulation” or “unique users” metric by 1 instead of 3. Even the “fingerprinting” of browser software to identify unique instances may fail to provide an accurate measure of circulation when multiple people are sharing a unique instance of the browser. While the traditional method of using surveys and panels may be used instead of digital measures to calculate the true audience, the use of such surveys will be just as flawed and inaccurate for digital content as for print content. Without having an accurate measure of the true audience size of a digital publication, publishers may be unable to demonstrate the true value of their digital publication content to prospective advertisers.